Potential difference and power (9.2)

What is voltage/potential difference?

Voltage - energy transferred per unit charge - measured in volts (V)

One volt is the same as one joule per coulomb

How is voltage measured?

A voltmeter is used to measure voltage

Voltmeters are set up in parallel to the part of the circuit you want to measure the potential difference across

How can voltage be calculated from its definition?

V = E/Q = W/Q

Where V is voltage (V)

Where E is energy transferred (J)

Where Q is charge (C)

Where W is work done (J)

What is electrical power and how can it be calculated from its definition?

Power - the rate of energy transfer - measured in watts (W)

P = E/t = W/t

Where P is power (W)

Where E is energy transferred (J)
Where t is time (s)

Where W is work done (J)

What is the relationship between power, current and voltage and what other relationships can be derived from this?

P = E/t = IVt/t = IV

Where P is power (W)

Where I is current (A)
Where V is voltage (V)

Other relationships:

1) Plug V = IR:

P = I(IR) = I²R

2) Plug I = V/R

P = (V/R)V = V²R

Where R is resistance (Ω)